When I traveled from San Diego > PA..(2945 miles) I really didn't have much with me sadly, it was filled with belongings when I was discharged. Although this is what I would bring along with me... Note I already owned some items, and then I bought things along the way that wasn't because of the road trip.

• Quality jumper cables. Get some low AWG ones, I own a set of 4 AWG and 2 AWG
• Oil. Personally I get a quart of the oil I just did a oil change on. I had ~ 2000 miles left on my oil before I needed to change it, I would've pushed it since I was doing all Highway miles, I got a oil change anyways.
• Small Air Compressor that runs off 12v/ Cig Lighter. Got one at Harbor Freight for $5 and works for when I need it really quick
• Windshield Wiper fluid.
• Car charger. A good USB one off your cig lighter. And also a AC-USB one just in-case the USB cig one fails

Inspection Items

• Tire tread is good, and tires are not dry-rotting
• proper air pressure. If you take a break at night and sleep somewhere, check the tire-pressure before you leave on the road again, takes < 5 minutes to do and can save your butt once you're on the road
• Serpentine belt. Look at the smooth side of the belt, make sure it doesn't looky shiny/glossy looking. Means the belt is wearing down and due to be changed. Also checked the ribbed side, if it's showing some large dry-rotted cracks also, time to change. 3rd thing to check is tension. You can tell if its loose or not. Kinda springy if you tap it or push on it.

Things I own that I didn't buy specifically for a road trip * Since I own a Dewalt 1/2 Impact, I take that with me now with the proper socket for my lug-nuts, 15mm for me at least iirc. * Enough e-juice for vaping along the way for me at-least * Valentine One. Saved my ass a few times going cross country.

Also, water. I know it may get boring after a while driving, but avoid soda as much as you can. Having a sugar high and coming down on a 1k single drive sucks hard.